1. Field of the Invention
The present subject matter relates generally to a wavelength selective switch (WSS) including a two-dimensional liquid crystal device such as a liquid crystal on silicon (LCOS), polysilicon, or an amorphous silicon backplane, and more specifically, to a WSS including an LCOS configured for use in an optical communication system.
2. Description of the Related Art
In optical communications systems, the use of wavelength selective switching for applications of optical cross-connects has attracted much interest because of the goal of fully flexible, networks where the paths of each wavelength can be reconfigured to allow arbitrary connection between nodes with the capacity appropriate for that link at a particular point in time.
It is known in the field of optical communications to use optical wavelengths as optical carriers for carrying digital or analog information. Also, the different wavelengths may be used to discriminate one set or channel of information from another. When a plurality of wavelengths are coupled or multiplexed onto a single fiber, this is called wavelength division multiplexing (WDM). Use of such WDM increases the overall bandwidth of the system. There is a need in such systems to switch packets of optical information passing along one fiber to any of a number of other fibers, according to the wavelength of the optical signal. Such a switch is known as an optical router or a wavelength selective switch. A number of wavelength dependent switches and routers exist in the prior art. For example, U.S. Pat. No. 7,092,599 to S. J. Frisken for “Wavelength Manipulation System and Method” describes a wavelength manipulation system using an LCOS phased array, with an optical arrangement including a spherical mirror and a cylindrical lens for maintaining collimation of the input beams in the direction of dispersion, and for focusing of the input beams in the direction perpendicular to the direction of dispersion. Also, in U.S. Patent Application Publication No. 2008/0316585 to G. Cohen et al. for “Optical Wavelength Selective Router,” there is described a fiber-optical, multi-way, wavelength selective switch (WSS) structure, such as is used for channel routing and/or blocking applications in optical communication and information transmission systems.